Coupling arrangement for components in subsea structures and a remotely operated tool unit for handling such components

ABSTRACT

Interface arrangement for components such as valves and control units incorporated in subsea stations particularly for hydrocarbon production, in which the components during operation are mounted in fixed positions on the subsea station and are adapted to be retrieved therefrom by means of a remotely operated tool unit unit (ROT) havign a mating interface arrangement to cooperate with that of the components. The upper part of the component, which is mounted for retrieval in a substantially vertical direction from its fixed position on the subsea station, is provided with central handling means and one or more coupling members. The handling means and the coupling members are adapted to cooperated with respective mating means and members provided on the ROT. Moreover, the handling means is dimensioned for lifting and transporting the component suspended from the ROT. The coupling members are movable up and down in relation to the handling means, when subjected to substantially vertical pull and push forces, respectively, applied from an ROT in an operative position connection to the component through the handling means, so as to effect an operation on the component, for example locking or unlocking thereof with respect tothe subsea station. The top of the handling means is provided with ports and/or connectors for hydraulic, pneumatic, optical or electric interconnection between the component and an ROT.

BACKGROUND OF THE INVENTION

This invention in general relates to an arrangement for interfacingretrievable subsea components particularly for hydrocarbon production,and a remotely operated tool unit (ROT) intended to cooperate with suchcomponents for performing operations thereon, for example locking orunlocking to/from the subsea structure and carrying a component betweenthe surface and its subsea location.

The components of interest in this regard may be of various types, suchas valves, control units or other types of separate retrievable units.During operations these components are mounted in fixed positions and insuch a manner that they may be retrieved by means of a remotely operatedtool unit (ROT).

OBJECTS AND SUMMARY OF THE INVENTION

An important aspect of this invention is a common interface to severalor all components concerned. The common interface has been devised inorder to limit the number of different installation tools for thevarious components.

The invention also comprises features related to the ROT as such, aswell as mechanisms belonging to some types of components, since theinterface arrangement to some extent will influence the structure andfunctions incorporated in both the ROT and the components concerned

Essentially this invention is directed to the task of making it possiblefor an ROT to access and interface a subsea structure with equipmentmodules installed therein, comprising retrievable components or units asmentioned above. A particularly important aspect in this regard is theability of an ROT to provide locking and unlocking forces to mechanicalconnectors fixing the retrievable components or units to matingconnector means on the subsea structure. However, also other operationson subsea installed components may be contemplated here.

A basic principle behind the solutions to be presented in the followingdescription, and in particular in the claims, may be seen in thegenerally vertical application of forces or vertical movements involved,this being related to the orientation of the components or unitsconcerned, these being mounted for retrieval in a substantially verticaldirection from a fixed position on the subsea structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made to the drawings, in which:

FIG. 1 somewhat simplified and in elevation shows a remotely operatedtool unit (ROT) embodying aspects of this invention

FIG. 2 shows the ROT of FIG. 1 from below,

FIG. 3 shows details on the same ROT as in FIGS. 1 and 2, landed on asubsea structure and interfaced with a subsea structure component foreffecting an operation on or with that component.

FIG. 4 is a vertical section showing the interface arrangement betweenthe ROT and the component in FIG. 3

FIG. 5 shows the ROT on FIGS. 1 and 2 handling another type ofcomponent,

FIG 6 is a vertical section through the interface arrangement betweenthe ROT and the component shown in FIG. 5,

FIG. 7 in elevation and partial section shows another example ofcomponent having an interface arrangement according to an embodiment ofthis invention, and

FIG. 8 in plan view shows a device for securing a component in an ROTduring transportation or retrieval.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The subsea ROT illustrated in the drawings, is a self-contained unitserving primarily as a manipulating and transport tool for theinstallation and recovery of subsea components. The ROT is usuallydeployed on a lift wire, or a drill pipe from a surface vessel, and isbuilt up within a support and protection frame more or less shaped as acage. Guidance and landing of such an ROT on a subsea structure willgenerally be by the conventional haul-down method, but a guidelinesystem or full thruster positioning may be used during deployment from asurface vessel.

As seen particularly in FIGS. 1 and 2, the illustrated embodiment of theROT has a cage-like support and protection frame 1 within which amanipulating tool comprising an interface arrangement is mounted. FIG. 2specifically shows haul-down winches 5 and 5A to assist in location andlanding of the ROT on a subsea structure or a part thereof. Thehaul-down winches cooperate with a heave compensator on the surfacevessel to eliminate the ROT heave motions. The ROT is also provided witha hydraulic power unit (not shown) for necessary hydraulic functions. Aswill be understood the ROT should further incorporate control andmonitoring equipment connected to an installation or vessel at thesurface by an electrical umbilical cable which includes a power supplyfor the hydraulic power units just mentioned, and including signalcables.

At the base of the supporting, structural frame or cage 1 there areintegrated two soft landing shock absorbers 23 and two hydraulicallyoperated lockdown mechanisms 24 for securing the ROT to a landingplatform or the like on the subsea structure. Externally on the frame 1there are provided two guide posts or guide funnels 2A and 2B which maybe retractable for handling purposes. At the top of the ROT there aremounted one or more hydraulically or electrically powered thrusters 3, 4for guidance of the ROT. For the possible use of guideline basedinstallation procedures, there are included two wire guides 6A, 6B (FIG.2).

On top of the cage 1 there is a transverse frame member 8 with a centralanchoring member or joint 9 from which there is suspended an elevatorassembly arranged to be moved in a longitudinal or height directionwithin the frame 1 guided by guide rods 11 and 12 along which can slidewing bearings 14 and 15 respectively, incorporated in the supporting ormain structure constituting the elevator. This structure also comprisesa transverse member 13. A hydraulic cylinder unit, shown at 10A in FIG.3, is connected to transverse frame member 8 and to the elevatortransverse member 13 for moving the elevator within frame 1. In FIG. 1the elevator or hydraulic cylinder is generally indicated at 10. Alocking device 8A with cooperating parts on the respective transversemembers 8 and 13, is provided for securing the elevator in its upperposition when carrying a component and also to restrict movement ofbearings or the like during transportation.

An essential feature of the interface arrangement incorporated in thetool carried by the elevator is a handling connector 16 aligned with thevertical or central axis AX of the ROT and elevator, and dimensioned forlifting and transporting any one of the components concerned, inparticular for retrieving such a component from the subsea structure tothe surface. For such operations the handling connector 16 is connectedto mating handling means in the form of a handling hub on the top of thecomponent.

The interface arrangement also comprises one or more coupling members orsmaller connectors 18A, 18B and 18C with associated hydraulic cylinders17A, 17B and 17C respectively, for moving connectors 18A-C up or downwith the central handling connector 16 remaining stationary. The smallercoupling connectors 18A-C with their respective hydraulic cylinders areused to connect to and operate mating coupling members in acomplementary interface arrangement on each of the components to beinterfaced with the ROT.

FIG. 3 illustrates a situation in which the central handling connector16 and the coupling connector members 18A, 18B and 18C have beenconnected to mating means and members at the top of a componentgenerally indicated at 40. This component is for example a choke valvethe stationary valve body of which is incorporated in a piping system ofthe subsea system concerned, through connecting conduits shown at 40Aand 40B with flange connections to the valve 40. At 44 there isgenerally indicated a level or plane at which the completed interfacearrangement between the ROT and the component may be considered to belocated. It should be noted however, that this interface will notgenerally comprise means or members all lying in the same plane. Infact, the interface arrangement comprises members being adapted to movein a direction normal to the interface "plane", i.e. vertically in FIGS.1 and 3. Further details of the interface arrangement will appear fromthe description of FIG. 4.

FIG. 3 also illustrates how the ROT is landed on a sort of platform 30having guide funnels 32A and 32B for the guide posts 2A and 2Brespectively, on the ROT. When referring to the landing area, theminiposts to which the ROT is secured and locked are not described norshown on the figure, The locking arrangement is shown on FIG. 1,24.Moreover there is an elevator access area defined by a wall 31underneath the platform 30, the top portion of valve component 40 beingaccessible through this area. Possibly the landing platform 30 withnecessary associated structure may be arranged on a fixed or removableroof element for a subsea structure as described in the applicant'ssimultaneous, U.S. patent application Ser. No. 07/684,942. Also as analternative, the landing platform 30 could normally be covered by asmall removable roof element as described in the application justmentioned, preferably with a roof element of such design that it can beremoved by means of the ROT itself.

Guide funnels 32A,B and posts 2A,B provide for a first step of coarseguidance for landing the ROT. A second and more exact guide function isobtained by means of two small posts projecting from platform 30 tocooperate with funnels associated with lockdown mechanisms 24 shownschematically in FIG. 1. One small post 24A is depicted below mechanism24 in FIG. 1. At 34 in FIG. 3 there is shown a post 34 entered into afunnel or mechanism corresponding to mechanisms 24 in FIG. 1. A lockingpin is hydraulically operated to enter a transverse hole in the smallpost, thereby locking and securing the ROT to the platform 30.

Obviously, the arrangement of guide funnels and posts can be invertedfrom what is just described. Thus, for example guide funnels 32A,B couldbelong to the ROT, with posts 2A,B projecting from platform 30, theformer arrangement, however, being preferred.

In spite of the two guidance steps explained, there may still be a needfor further accuracy when installing a component on a subsea structurewith an ROT. Therefore, as will appear in particular from FIGS. 4 and 6,the component is also provided with guide means, such as guide pins fora third and final alignment step with respect to the housing or socketin which the component shall be mounted. In order to make this finalalignment possible, taking into account unavoidable tolerances inlanding and component arrangements as well in the ROT structure itself,the ROT elevator 10 with interface connectors 16 and 18A-C is suspendedwith some degree of play or float laterally. This is provided for (seeFIG. 1) by bearings 14, 15 sliding on rods 11, 12, and supportingmembers 9,13.

At the top of the ROT in FIG. 3 there is shown a wire or cable 7extended to the surface, for hoisting the ROT and possibly forelectrical connections therewith. The dry weight of the complete ROTwill for example be approximately 4 tons with a height of perhaps 4meters, whereas the width may be from 1,5 to 2,0 meters. Thesedimensions of course depend on the size and weight of the components tobe handled and retrieved.

Turning now to FIG. 4 the valve 40 is seen to comprise a valve body orhousing 41 into which a retrievable valve insert assembly generallyindicated at 42, can be mounted. This can for example be a choke valve,the critical parts of which from time to time must be retrieved to thesurface for maintenance and the like. Thus, strictly speaking, the"component" referred to above (FIG. 3), in this example is representedby the retrievable insert assembly 42, substantial parts of which arelocated outside the valve cavity within body housing 41, i.e. above thishousing.

At the top of this component there is provided a handling hub 49 havinga shape and dimensions adapted to be engaged by the handling connector16 of the ROT. In addition to handling hub 49 the interface arrangementof the component comprises three coupling members or mandrels 48, ofwhich one is shown in engagement with a respective coupling connectormember 18A in FIG. 4. The connections 16,49 and 18A,48 may be of more orless conventional designs, which makes possible the transfer of bothpush- and pull forces thereby. What is of particular interest in thepresent context is the essentially axial or vertical movements and forcedirections involved, which is of significance in view of the retrievalof the components in a substantially vertical direction from a fixedposition on the subsea structure, as mentioned above.

Before studying further details of the interface arrangementsillustrated in FIG. 4, it should be noted that the left-hand part of thedrawing illustrates the mechanism in a position in which the valveinsert or ccmponent is unlocked from the valve housing 41, whereas inthe right hand part of the drawing there is established a lock betweenthe valve insert 42 and the housing 41. This locking is provided for bya connector assembly 43 comprising movable locking pieces 43A designedfor cooperation with corresponding locking abutments 41A at the upperpart of housing 41. Locking is obtained by pushing down a sleeve 45which by means of inclined internal camming surfaces 45B thereinengaging surfaces 43B on the locking pieces 43A, move these into theposition illustrated at 43A as shown in the right-hand part of FIG. 4.

The necessary push-down force for moving the sleeve 45 from the upper(or left-hand) position in FIG. 4 to the lower (or right-hand) positionis exerted by the hydraulic cylinders 17A-C through the couplingconnector members 18A-C. The mandrels 48 are mounted on a common yoke orannular plate 44 at the underside cf which the above sleeve 45 ismounted. The yoke or plate 44 is referred to above in connection withFIG. 3, as the level or "plane" of the interface arrangement.

For releasing locking pieces 43A when the sleeve 45 has been retractedupwards as shown in the left-hand part of FIG. 4, unlocking is providedfor by cooperating inclined surfaces 45A and 43C bringing about arocking motion of locking piece 43A, thereby displacing the lower endthereof to be disengaged from abutment 41A.

On the top surface of handling hub 49 there are shown ports orconnectors 36B and 37B forming a significant part of the interfacearrangement belonging to the removable or retrievable component 42including the connector mechanism 43. For cooperation with ports orconnectors 36B, 37B, the handling connector 16 of the ROT on matingsurface is provided with corresponding ports or connectors 36A and 37A,for example in the form of stabs adapted to enter into respective portsin the handling hub 49. Whereas such handling hubs may have a differentnumber and arrangement of such ports or connectors, depending on therequirements of the component concerned, the handling connector 16 musthave a complete or full number and arrangement of such ports andconnectors to enable it to interface the various components which it maybe of interest to handle.

FIG. 5 shows the ROT as described above with respect to FIGS. 1, 2 and3, having retracted component 60 by means of the elevator, completelywithin the supporting frame 1, for example in order to retrieve thecomponent to the surface from a subsea station. Component 60 may be aretrievable valve insert as described in simultaneous U.S. patentapplication Ser. No. 07/684,941. The mating or common interfacearrangements, as generally indicated at 55 in FIG. 5, in this case alsocomprises the central ROT handling connector 16 engaging a handling hubat the top of component 60, and coupling connector members 18A-Cengaging coupling members or mandrels projecting upwards from an annularyoke similar to the one shown at 44 on FIG. 4. Further details withrespect to component 60 in FIG. 5, will be described below withreference to FIG. 6.

For securing ccmponent 60 during transportation and retrieval to thesurface by means of the ROT, there are provided supporting or clampingdevices 90A and 90B mounted on the frame 1 and adapted to laterallyengage and secure component 60 when suspended from the elevator. FIG. 8shows more in detail an embodiment of such devices. Thus, in FIG. 8 onedevice 90A is shown as a whole, whereas device 90B is only partlyincludes in the drawing. The plan view of FIG. 8 schematically showsccmponent 91 which is engaged by two clamping shoes 92A and 92B,preferably engaging component 91 from opposite sides. As indicated at 93these shoes may have a resilient padding or cushion so as to avoiddamage to component 91. Clamping shoe 92A is pivotably attached to alever arm 94 being journalled at 95 and having an opposite end 96connected to the piston rod of an actuator cylinder 97, thus providingfor the necessary clamping movement cf shoe 92A against component 91. Asupporting plate or frame 98 may be adjustably mounted within the ROTframe 1 to adapt the device to different component diameters.

Component 60 (FIG. 5) shall now be described somewhat more in detailreferring to FIG. 6. Main parts of this component are valve insert 62for a ball valve, connector means 63 for locking to a valve housing, anda valve actuator 64. The same main parts are illustrated and furtherdescribed in the above simultaneous patent application.

Connector 63 is joined to valve insert 62 by bolts 67. A guide pin 69 isadapted to cooperate with a corresponding guide hole in the valvehousing. The interface arrangement here is composed of handling hub 89and three mandrels 68 spaced 120° around the periphery of an annularyoke 66, which is in turn being movable in a vertical direction in FIG.6, in relation to handling hub 89.

A number of push-pull rods 81 have their upper ends connected to yoke 66and are slidable in bores 80 to bring about lateral movement of lockingpieces 84 having teeth or grooves in the external surface intended forengagement with correspondingly shaped locking means inside the valvehousing into which the component or valve insert is to be mounted. Inthe position illustrated in FIG. 6, yoke 66 and therefore rod 81 hasbeen pushed down and accordingly locking piece 84 assumes its lockingposition. This transformation of the axial or vertical movement of rod81 to the lateral movement of locking piece 84 is brought about byinterengaging inclined surfaces as indicated at 83 at the lower endportion 82 of rod 81 and at the inner side of locking piece 84respectively. These inclined surfaces 83 may be in the form of a groovedprofile enabling positive outward as well as inward displacement oflocking piece 84. Thus, a pulling force applied to mandrels 68 from anROT interface, moving push-pull rod 81 upwards, results in inwardmovement of locking piece 84 so that unlocking cf the component isobtained.

The connector means briefly described above is more fully covered by thesimultaneous U.S. patent application Ser. No. 07/684,943.

At the top surface of handling hub 89 there are indicated ports orconnectors 86, 87 which interface with mating ports or connectorsarranged in a bottom surface of the ROT handling connector.

Turning now to FIG. 7, a further type of component 70 is schematicallyshown. This may be a control unit or control pod containing necessaryparts and equipment for various control functions pertaining to a subseastation or subsea station module. This component, like the abovedescribed components, is provided with a handling hub 79 the axis ofwhich is also a central axis of the complete component 70. To the leftof axis AX there is shown a yoke member 77 with a connector mandrel 78Bin a lower position, whereas at the right-hand side of axis there isshown a mandrel 78A in an upper position. It will be realized thatmandrels 78A and 78B, as well as one or more additional mandrels in thisinterface arrangement, may all be constrained to move in unison by beingmounted on the common yoke 77. Push-pull rod 76 is provided fortransferring push-pull movements or forces into component 70, possiblyfor performing locking or unlocking thereof with respect to the subseastation.

We claim:
 1. An interface arrangement, provided on a retrievablecomponent incorporated in a subsea structure, for coupling saidcomponent to a mating interface arrangement of a remotely operated toolunit (ROT) which retrieves said component from a fixed position on saidsubsea structure, said mating interface arrangement of said ROTincluding a plurality of coupling devices, said interface arrangementcomprising:(A) a central handling means, provided on an upper portion ofsaid component, for lifting and transporting said component, saidhandling means being provided with at least one of ports and connectors,said at least one of ports and connectors providing at least one ofhydraulic, pneumatic, optical, and electrical interconnections betweensaid ROT and said component; (B) a plurality of coupling members whichare laterally and symmetrically offset from an axis of said centralhandling means and which selectively cooperate with said plurality ofcoupling devices so as to allow said ROT to manipulate said component;and (C) a yoke member which interconnects said plurality of couplingmembers so as to allow said plurality of coupling members to be moveablein unison up and down in relation to said handling means when subjectedto substantially vertical push and pull forces from said ROT.
 2. Thearrangement as claimed in claim 1, wherein said plurality of couplingmembers comprises three coupling members spaced 120° apart about saidaxis of said handling means.
 3. The arrangement as claimed in claim 1,wherein said interface arrangement cooperates with said subsea structuresuch that said push force causes one of locking said component to saidsubsea structure and unlocking said component from said subseastructure, and said pull force causes the other of locking saidcomponent to said subsea structure and unlocking said component fromsaid subsea structure.
 4. The interface arrangement according to claim1, further comprising connector means for locking and unlocking saidcomponent to and from said subsea structure, and a push-pull elementwhich is connected to at least one of said coupling members and whichactuates said connector means, said connector means comprising a lockingpiece which moves laterally when actuated by said push-pull element andwhich is engaged with and disengaged from a mating locking device onsaid subsea structure.
 5. The interface arrangement according to claim4, further comprising an inclined cam surface which is provided on oneof said push-pull element and said locking piece and which transformsaxial movement of said push-pull element into lateral movement of saidlocking piece.
 6. The interface arrangement according to claim 5,wherein said cam surface is provided at such an angle in relation tosaid axis that said locking piece will remain locked in a position inwhich it is engaged with said locking device unless it is subjected tosaid pull force.
 7. The interface arrangement according to claim 1,further comprising connector means for locking and unlocking saidcomponent to and from said subsea structure, and a plurality ofpush-pull rods which are larger than said coupling members, which areconnected to said coupling members, and which actuate said connectormeans, said connector means comprising a plurality of locking pieceswhich move laterally when actuated by a corresponding one of saidpush-pull rods and which are selectively engaged with and disengagedfrom mating locking devices on said subsea structure, each of saidpush-pull rods having a first end which is connected to said yoke memberand a second end which actuates the respective one of said lockingpieces.
 8. A system comprising:(A) a retrievable component which isincorporated in a subsea structure and which has a first interfacearrangement provided thereon; and (B) a remotely operated tool unit(ROT) which retrieves said component from a fixed position on saidsubsea structure, said ROT having a second interface arrangement forcoupling said ROT to said first interface arrangement and formanipulating said component, said second interface arrangementincluding(i) a central handling connector means for lifting andtransporting said component, said central handling connector meanshaving a lower part which is provided with at least one of ports andconnectors, said at least one of said ports and said connectorsproviding at least one of hydraulic, pneumatic, optical, and electricalinterconnections between said ROT and said component, (ii) a pluralityof coupling connector members which are laterally and symmetricallyoffset from an axis of said central handling connector means and whichselectively cooperate with said first interface arrangement so as toallow said ROT to manipulate said component, and (iii) activation meansfor moving said coupling connector members up and down such that saidcoupling connector members apply substantially vertical pull and pushforces on said component when said ROT is connected to said componentthrough said handling connector means.
 9. The system as claimed in claim8, wherein said plurality of coupling connector members comprises threecoupling members spaced 120° apart about said axis of said handlingconnector means.
 10. The system as claimed in claim 8, wherein saidactivation means comprises a plurality of hydraulic cylinders, each ofwhich is connected to one of said coupling connector members.
 11. Thesystem as claimed in claim 8, wherein said ROT comprisesa supportingframe, guide posts, mounted on said supporting frame, for landing saidROT on said subsea structure; means for controlling and guiding saidsupporting frame from the surface; and an elevator which is mounted forvertical movement within said supporting frame and which carries saidhandling connector means and said coupling connector members.
 12. Thesystem according to claim 11, wherein said elevator is capable oftravelling to an upper vertical position for retracting said componentcompletely within said supporting frame.
 13. The system according toclaim 12, further comprising means for securing said elevator in saidupper vertical position within said supporting frame so that saidcomponent is secured within said supporting frame for transporting. 14.The system according to claim 11, further comprising means for laterallyengaging and securing said component to said elevator such that saidcomponent is suspended from said elevator and is secured within saidsupporting frame so that said component can be transported in a secureand protected manner.
 15. The system according to claim 11, wherein saidelevator is moveable laterally with respect to said axis of saidhandling connector means when said elevator moves vertically within saidframe so as to allow corresponding lateral movement of said component,and further comprising guide means for laterally moving said componentwith respect to said supporting frame to align said component formounting on said subsea structure.
 16. The system according to claim 11,wherein said guide posts provide a first step of coarse guidance of saidcomponent, and further comprising guides which are smaller than saidguide posts and which provide a second step of more precise guidance ofsaid component onto a landing area of said subsea structure and whichlock said component to said subsea structure.
 17. An interfacearrangement, provided on a remotely operated tool unit (ROT) whichretrieves a component from a fixed position on s subsea structure, forcoupling said ROT to a mating interface arrangement on said componentand for manipulating said component, said interface arrangementcomprising:(A) a central handling connector means for lifting andtransporting said component, said central handling connector meanshaving a lower part which is provided with at least one of ports andconnectors, said at least one of said ports and said connectorsproviding at least one of hydraulic, pneumatic, optical, and electricalinterconnections between said ROT and said component, and (B) aplurality of coupling connector members which are laterally andsymmetrically offset from an axis of said central handling connectormeans and which selectively cooperate with said mating interfacearrangement of said component so as to allow said ROT to manipulate saidcomponent; and (C) activation means for moving said coupling connectormembers up and down such that said coupling connector members applysubstantially vertical pull and push forces on said component when saidROT is connected to said component through said handling connectormeans.
 18. The interface arrangement as claimed in claim 17, whereinsaid plurality of coupling connector members comprises three couplingmembers spaced 120° apart about said axis of said handling connectormeans.
 19. The interface arrangement as claimed in claim 17, whereinsaid activation means comprises a plurality of hydraulic cylinders, eachof which is connected to one of said coupling connector members.